1. Field of the Invention
The present invention relates to a method of manufacturing a card-type storage device and a card-type storage device. In particular, the present invention relates to a technique for facilitating manufacturing a frame that supports a semiconductor memory, and for enabling the storage device itself to indicate contents stored in the storage device, in a thin type card-type storage that incorporates a semiconductor memory.
2. Description of the Background Art
FIGS. 1 and 2 show the structure of a conventional standard card-type storage device, in which FIG. 1 is a perspective view and FIG. 2 a sectional view.
This type of storage device is disclosed in, for example, U.S. Pat. No. 5,550,709.
A conventional technique for manufacturing such a card-type storage device injection-molds a card-type frame 111 of solid body from plastic. The frame 111 has an opening 111a to receive a memory module 113. The memory module 113 has a semiconductor memory 113a and a flat electrode 113b and is fitted into the opening 111a of the frame 111 to be fixed such that the flat electrode 113b is exposed.
Above-mentioned conventional technique for manufacturing the car-type storage device, however, has the following problems.
Apparatuses such as digital cameras that employ card-type storage devices are becoming smaller, and therefore, the card-type storage devices are required to be smaller and thinner. In the thin storage device of FIGS. 1 and 2, the frame 111, which is injection-molded into solid body, must have a very thin recessed bottom 111b under the opening 111a for receiving the memory module 113. To form such a thin bottom 111b, a precision metal mold must be prepared through difficult processes, and the inside of the metal mold must be kept under a low pressure when injecting resin into it. This complicates the structure of a molding mechanism and makes the resin injection work difficult.
There is a risk of injection-molding the thin bottom 111b into an unwanted shape depending on resin material used for the frame 111. More particularly, to correctly form the thin bottom 111b, molten resin must be injected into the corners of a metal mold. To achieve this, the resin must be heated to reduce the viscosity thereof and must be injected into the injection point of the metal mold with great pressure. At this time, however, the resin will burn due to frictional heat if the resin has low heat resistance. If heat-resistive resin is used to avoid the problem, it may deform the thin bottom 111b because the heat-resistive resin has high viscosity.
There are only limited resin materials that may correctly form a card-type frame having a thin recessed bottom. Such materials include MULTIRON TN-3813-B of Teijin Chemical Company. This resin material, however, has limited applications because it is incapable of forming transparent or translucent card-type frame that withstands a high temperature of 100 degrees centigrade or higher.
In this way, the conventional technique is hardly capable of manufacturing thin, small card-type storage devices having a thin recessed bottom 111b.
Making a card-type storage device with transparent or translucent material provides an advantage to show an image printed on the storage device to a user so that the user may easily recognize the contents of information stored therein, as a characteristic of above mentioned card-type storage device. However, the conventional technique allows only limited materials to form card-type frame 111 of solid body. Accordingly, the conventional technique is unable to freely form transparent or translucent card-type storage devices to meet various applications for card-type frame thereof.